On Fri, Aug 31, 2001 at 08:39:29PM +0100, tonyl wrote:
On Friday 31 Aug 2001 20:18 pm, Jim Penny wrote:
Yes, I am saying that the version I have crashes once or twice a week. No, it does not make it at all unusable. There are 86400 minutes in a week. this makes it available 99.9976% of the time. It is automatically restarted after a minute without response goes by, so I do not have to be here, etc.
What planet are you using zope on Jim.? Your days last a real long time (or my maths is awful) ;-)
Ah damn, that is seconds per week. (Too used to thinking in seconds.) Make that 99.86% availablity.
Apache in my experience is better in terms of uptime. But I have had it crash, too. I have had PostgreSQL crash. I have has AS/400 services crash. Once you get beyond 3 9's of uptime, it starts to cost money. I am running on clone hardware with no ECC, etc. Prepare not to have 99.999% uptime, and you can handle 99.99% uptime quite well.
For me, the issue is which of those minutes it's out of action. In my situation, the application will be hammered at the start of the month, week and morning (in that order). Most of the available minutes for statistical purposes won't have much in the way of system activity. So 1 minute in peak time is quite a high %age for the project. The equipment will probably be an 8 way sun box with oracle.
Look, you are running on way more hardware with way better and way more expensive gear than I am used to. It sounds like you have an actual budget. If you can't get better uptime, I would be surprised. I come from a different situation entirely. In my situation, if it can't be done with hand-me-down hardware and a bit of sweat equity, then it can't be done. Also, all of that activity sounds like read activity. Read activity, in my experience, hardly ever triggers problems. at least 90% of my problems have been write related. (And I still would be a bit surprised if your user base is upset by an occaisional minute of downtime. The web has trained people way too well that downtime is normal!)
I guess it has a user definable check-zope-is-up period? I'll soon change it if it hasn't! (if I can).
It can be shortened, but beware (a bit). You do not want the period so short that zope cannot completely be reawakened. That is, you do not want to start hammering a restart process so hard that it starts taking down processes before they can start responding. Jim Penny
Thanks, Tony